I have plans, and these include upping the boots from 265/65R17's to 285/70R17.

Currently the standard rims are 17X8 P55 and there stuff all inner clearance with the standard treads on. If I was to go to 285's I would think that I would need a lower offset rim? I was thinking of going to a P35 offset, which according to the various calculators some of you blokes have put up, will give me another 20mm inner clearance, which obviously means that 20mm will now be poking outwards.

Now considering the tyre will only be 20mm wider than the standard this means only 10mm of that 20mm inner clearance will be used, with the additional 10mm poking out further from the vehicle for a total of 30mm each side.

Been into my local tyre shop about fitting those tyres and he's not too keen, illegal diameter increase he said. Apparently you can legally (in QLD) increase rolling diameter by 50mm, doing the changes I want would exceed this by just 4.36mm, so about 20thou km's to wear the tread.

I am well aware of the changes in vehicle behaviour this would cause, including braking, odo, speedo, fuel economy etc But eventually want to push ahead with this, already started planning for a trip to the cape next year!!

The lack of clearance worried me as well. I ended up swapping to a 16x8 with around a +30 off set with 265/75/16 Federal MTs. Clearance is much improved, the overall rolling diameter has increase just under an inch as well. Speedo has been affected in a good way and is now only a couple km/h out (GPS tested) instead of about 6 or 7 km/h.

The tyres sit flush with the guards, maybe a little out, but nothing noticeable. Stepping up to a 275 or 285 will require flares to keep them covered.